The Academy Awards ceremony is Hollywood's biggest glamorous event.
Literal
Academy-award-ceremony [topic-は], Hollywood-greatest [possessive-(omitted)] glamorous event is.
Straightforward descriptive sentence. 華やか (はなやか) is a na-adjective meaning 'showy, gorgeous, glamorous' — literally 'flower-like'. 催し (もよおし) is a more formal/literary word for 'event, gathering' compared to the everyday イベント.